Boxxer Race fork - what front hub width?

I bought a new Boxxer Race dual crown fork to install on a DH frame. I had a set of wheels:
Front wheel: Sun Demon hub, 20mm thru axle,
Rear wheel: Sun Demon hub, 12mm axle, 150mm width
The front wheel slides around in the front axle. It's way too narrow for the width of the front axle. Should I have adaptors to make it fit in there? Or do I need to go to a wider front hub?
Here's the hubset:http://www.sun-ringle.com/contentpag...reeridedh.php5
Here's the fork (no information on hub size):http://www.sram.com/en/rockshox/downhill/boxxer/#tab3
Someone know what I need to do to the front wheel?
Thanks,
J

I bought a new Boxxer Race dual crown fork to install on a DH frame. I had a set of wheels:
Front wheel: Sun Demon hub, 20mm thru axle,
Rear wheel: Sun Demon hub, 12mm axle, 150mm width
The front wheel slides around in the front axle. It's way too narrow for the width of the front axle. Should I have adaptors to make it fit in there? Or do I need to go to a wider front hub?
Here's the hubset:http://www.sun-ringle.com/contentpag...reeridedh.php5
Here's the fork (no information on hub size):http://www.sram.com/en/rockshox/downhill/boxxer/#tab3
Someone know what I need to do to the front wheel?
Thanks,
J

All 20mm through axle hubs are 110mm wide. Sounds like you are missing at least one of the end caps (as shown on the Sun site it is missing one).